Marlon 16mm Opal Triplewall Polycarbonate Roof Sheet 4000mm x 700mm x 16mmProperties Excellent protection: against hailstones, vandalism and accidental damage. Virtually opaque sheet: desirable feature in built up areas. Provides: a private setting with a soft light quality. Reduces glare: especially important for studying or working. Eliminates: sun hotspots but keeps the environment bright. Light transmission: 42% means you can still enjoy the benefits of the sun. Up to "Class 1" fire rating: polycarbonate is a self-extinguishing material which will melt away from the flames, stopping as soon as the source is removed. Note: 6mm Twinwall does not have a Class 1 fire rating. High strength: weight ratio. Cost effective: as sheet weight is low, support structures can be lighter providing cost effective buildings.Corotherm provides high levels of insulation.